Slayer's Testament
by beitrik
Summary: The Incubators create warriors, but their contracts always came at a cost. Doomguy origin story (Doom 2016)
1. Wish

_They are rage, brutal, without mercy._

 _But you. You will be worse._

 _Rip and tear._

 _Until it is done._

* * *

Long before the Incubators discovered Earth and settled upon using Human Females as their victims, other intergalactic races were considered to be their guinea pigs for their energy harvesting plan. One such race was the people of the doomed planet, Argent D'Nur.

As a young child, Ta'Gart D'Nur admired the Night Sentinels who guarded his hometown without fail. Courageous and noble, the Knights of Argent were respected by all. Much to Ta'Gart's dismay, however, there was no known means of recruiting into the prestigious order of warriors, but he never gave up hope. In fact, hope was what kept him running day after day.

And that hope eventually manifested into the greatest adventure he could never imagine.

All it took was the discovery of a mysterious white object sitting outside the porch of his home. _That's strange_ , he thought, _I've never seen anything like this before_. Suddenly, the object uncurled itself to reveal a long, bushy tail, and a head with cat-like ears and two floppy appendages hanging from their sides. The creature looked at the fascinated Ta'Gart with unblinking, pink eyes.

"Who... are you?"

Without warning, the creature answered back. "My name is Kyubey!" Ignoring Ta'Gart's startled expression, the Incubator continued. "I'm here because you, Ta'Gart D'Nur, have the potential to be a Night Sentinel!"

Ta'Gart was amazed. He pictured himself donning the pristine Sentinel armour, striking down demons swiftly with his Holy Sword. He envisioned himself striding down rows of Sentinels, saluting at the very sight of his presence. And now, this creature - whatever it was - had offered him this extraordinary opportunity. He couldn't resist!

"R-really?"

"Of course! All you have to do is make a contract with me, and I will grant you any wish! In turn, you will have to do your duty as a Night Sentinel of Argent D'Nur."

Ta'Gart took a deep breath. Being a Night Sentinel in itself was already a dream come true, but what else could he wish for? Perhaps...

His mind raced with ideas. How exactly did the idea of being a Night Sentinel appeal to him? Their strength and courage? The brotherhood amongst their ranks? The respect bestowed upon them by the Argent people?

After a while of deep thinking, Ta'Gart realized his wish. He gazed into the Incubator's cold expression with a confident flame within the pits of his eyes.

"I wish... I could be the greatest Night Sentinel ever. I wish I could be the strongest, bravest, most respected warrior in all of Argent D'Nur!"

A flash of light temporary surrounded the boy as his face contorted with agony. What was going on? Wasn't he supposed to become a Night Sentinel? Forcing his squinted eyes to open slightly, he noticed that within his palms lay a beautiful egg-shaped object, plated with gold and bearing a bright green hue.

After what seemed like an eternity, the pain subsided and the exhausted boy was left sprawled on the ground, panting, his heart beating against the walls of his ribcage.

As Ta'Gart struggled to get up, he noticed something... Different about his clothes. He glanced down upon himself and almost jumped in surprise. He was no longer wearing the traditional villager's garb, but a set of silver armour that gleamed in the golden Argent sunlight. In the palm of his right hand nestled the handle of a broad sword, its edge the sharpest he has ever seen. Testing the weapon's weight, tears of joy started to prickle within his eyes.

 _No way..._

"Your wish has overcome Entropy. Now, go unleash your new power!"

Ta'Gart dropped onto his knees and wept. He couldn't believe it. He was officially a servant of the people, one of the few noble protectors that kept Argent safe. He dreamed of being a hero for years, and here he was, taking his first steps into Knighthood as an honourable warrior.

This was, without a doubt, the best day of his life.

* * *

 **A/N**

 **Bonus points if you can get the reference behind Doomguy's name.**

 **Also, I understand that the idea of this crossover may not sit well with everyone. I respect your opinion if you don't like this story or even the concept of this story, but I will not appreciate trolling or flames in my inbox.**

 **Till next time.**

 **\- Beitrik**


	2. Luxury

Years passed in the twinkling of an eye. Captain Ta'Gart of the Night Sentinels became one of the most respected warriors on the planet. Whenever duty called, he would lead his team - a squadron of strong, courageous men - to battle against the forces of evil, the demons from Hell itself.

He recognized their unholy forms after countless battles. The agile Imps, the floating Cacodemons, the brutish Hell Knights and bloated Mancubi... No matter what the threat was, Ta'Gart always had a strategy to deal with it. Such was his prowess as a soldier and a tactician that his comrades knew him as **"The Doom Slayer"** \- a living nightmare to the forces of Doom.

It was without saying that being a Night Sentinel was a dangerous job. Most of Ta'Gart's days were spent training, if not on the battlefield. He had certainly been close to death many times as he fought against the demons' ferocity. It didn't matter to him, however. He loved being a Night Sentinel. He loved being a hero, protecting his people from otherworldly dangers. And he loved his men - brothers in arms that would put their lives on the line for him, and that he would do for them as well. He did not just see them as his soldiers, but as his own sons, brothers, friends.

This life was almost perfect for him, and he would never trade it for anything else.


	3. Downfall

_Years later..._

Ta'Gart dashed through the streets, holding his sword and ready to strike at any demons incoming. Even with his aching legs threatening to give way at any moment, he still sprinted as fast as he could.

The attack occurred without warning. Just mere moments ago, the city of Argent was as bustling as it had been every other day. The marketplace was swarming with patrons while children were playing catch in the alleyways, their boisterous laughter rising above all others.

Then everything changed in the blink of an eye. The once beautiful town - his town - had been reduced to flaming rubble and brimstone. The screams of terrified men, women and children shot up into the bleak, crimson skies.

Ta'Gart roared as he swung his Holy Sword, decapitating an Imp with little difficulty. Two more spring up behind him, taking the soldier offguard as he tumbled to the ground with a grunt. Wincing as the monsters mercilessly slashed and hacked at his armour, he threw them off with brute force and pummeled them with his stone-like fists. Their bloodied and torn remains hit the ground with a limp thud.

 _Why... How could this be happening?_

No matter... He had to fight on. He was, after all, a Night Sentinel. A soldier. And a true soldier never gives up.

As he was about to turn, however, his path was blocked by a certain cat-like creature.

"Kyubey, move!"

"How fascinating. I never expected things to go haywire so fast."

Its emotionless voice irked Ta'Gart even further. He really wasn't in the mood for whatever the bunnycat had to say. "I said, MOVE!"

 _Wait._ The Incubator's words replayed in his mind...

The Sentinel's face contorted in rage. "You knew this was going to happen?!"

"Of course," Kyubey replied in its standard monotonous, high-pitched drone. "The reason why Argent D'Nur is under attack by the demons is because one of your men made a deal with a Priest of Hell, Deag Grav. I was around when it happened. He wanted his dead son back..."

"And you didn't stop him?! Why?"

At that point, Kyubey tilted its head towards the enraged Ta'Gart, whose blood was boiling within his veins. He ground his teeth in disgust as delivered a glare of pure hatred at the creature's smug expression.

"I would have stopped him if it was pointless to do so. But the opportunity to harvest so much emotional energy was just too prime to pass up! The destruction of a single planet housing complex lifeforms as yours will generate huge amounts of fuel.." Ta'Gart's facial expression, a mix of confusion, anguish, and rage, led Kyubey to halt its rambing. "Oh, I suppose you do not understand what I'm talking about. Fine, I guess I'll start explaining. Do you know what 'Entropy' means?"

 **"I don't know and I don't fucking care!"** His bellowing roar echoed throughout the devastated wasteland. **"You bastard! How could you do this to us?!"**

"You also forgot one crucial detail, Ta'Gart D'Nur."

Ta'Gart's muscular arms shuddered as his hands balled themselves tightly into fists.

"When you made your wish, you wished to be the most respected warrior in Argent D'Nur. However, you did not wish for loyal comrades, did you? I simply kept my part of the bargain. Everything else is up to..."

 **WHAM.**

A sickening crunch filled Ta'Gart's ears as his fist landed atop the Incubator's head, crushing its skull. Blood gushed out from the bunnycat's limp form, staining his hand with sticky red liquid. Ragged breaths escaped the broken man's lips as he fell to his knees in grief. His Soul Gem was roiling with dark impurities, cracks beginning to form at its surface.

When he made his wish, he was young, foolish and impulsive. His ambition to be a Night Sentinel was so powerful and driving that it blocked out any sense of reasoning in his mind, and he instead leapt at the opportunity without thinking.

All he wanted to be was a hero. To protect the people. Was that so hard to ask for? Why did it have to end this way? The very thing that he lived for was now gone... All due to that creature!

Unable to bear the grief welling up in his heart, Ta'Gart D'Nur gazed at the sky and let out a bloodcurdling scream. Every tear, every regret, every single one of his fallen comrades, all let out in one mighty cry.

At the same time, his Soul Gem began to shatter.


	4. Crusade

_Ugh... What happened..._

Ta'Gart attempted to get up unsteadily on shaky footing.

 _Legs like jelly... Fingers feel numb... Mother of all headaches..._

Forcing his head downwards, he noticed that his Night Sentinel Armour was mostly intact, but in a state of severe disrepair. Its once silver gleam had turned a murky shade of dark grey, and cracks and crevasses in the metal revealed the man's tanned skin. His sword was gone, and in its place was a red, anvil-shaped artifact with a skull carving on both sides.

What exactly happened? All he remembered was a devastating explosion as his Soul Gem splintered into a million pieces...

Ta'Gart blinked. Something about him seemed different. A steady stream of energy ran through his veins; his body shook and shuddered as he tried to control the inexplicable urge to destroy. Arcane voices echoed within his head, their seductive whispers fueling his desires. The only thing stopping him from doing anything was his confusion.

Ta'Gart looked around the vast landscape as he shambled around. Broken pillars and stone littered the area. Mutilated corpses were strewn about; staining the scorched ground red. It was truly a horrifying sight, and the stench of decay looming around did not help in the slightest.

Ah, he remembered now. His former hometown, Argent D'Nur. Utterly decimated by the demons due to a traitor amongst his men.

He failed. He failed to protect his people. He was a complete and utter disgrace.

No. He was already a fool from the beginning. He should have known that Kyubey's deal had been too good to be true. If only he could go back in time...

A guttural growl escaped his throat. Ta'Gart stopped. How could he have made such a sound? It sounded otherwordly, menacing... Demonic, even.

Ta'Gart looked down at his body in alarm. His skin... While his skin tone had been the same as before, it seemed much tougher with a texture that he could only describe as reptilian.

He started to pant heavily in fear as his heart began racing. What had he possibly become? How had he become this way? He no longer felt Argent, so what was he now?

As confusion began to overwhelm the man, the chanting in his head grew even louder.

 _"Oremor nhoj, em llik... Emag eht niw... Rip and tear... Rip and tear!"_

Then realization hit him like a ton of bricks.

A monstrous howl escaped Ta'Gart's lips as he took off into the wasteland, leaving behind the carcass of a city never to thrive again.

* * *

Ta'Gart ran.

He knew not how long he had been running.

He knew not where he was going.

But he still ran.

He wanted out. Away from this nightmare. Away from this Hell.

Away from the demon he had become.

His powerful legs drummed along the sandy Argent soil, leaving clouds of red dust in his wake. His gasping breaths released wafts of sulfur into the humid atmosphere. He felt disgusted with himself, more than ever. The very thing he had wanted to protect himself and his city from... He was one of them now.

 _All because of that bastard Incubator._

Falling to his knees, Ta'Gart roared as he pounded the ground with his fists. Cracks and dents formed in the rusted soil as he attacked it mercilessly, venting his unrelenting fury upon the earth.

Ta'Gart was now a demon. A slave of evil. The cause of all despair in the universe. All he could look forward to was an eternal future of destruction, violence and rage. It was his only future, but it was also a future he would never accept.

"Fuck! Fuck, fuck, fuck, **FUCK!** "

His screams echoed into the emptiness of the desert, with no audience to receive his wrath. It felt like a million needles were pricking at his mind, each one injecting into him volumes of regret.

 _How funny_ , he thought. _It was hope that led me to become a Night Sentinel. And being a Night Sentinel led me to this despair._

A sudden hissing noise made him bristle in surprise. Slowly tilting his head backwards, he came face to face with three Imps. The orange humanoid creatures were glancing at him with glowing yellow eyes, their faces betraying a non-hostile look.

Ta'Gart bared his teeth.

"What do you want, demon scum?!"

 _"Come with usssss..."_

His eyes narrowed as he clenched his hands tightly, ready to pummel these bastards into oblivion.

 _"You're one... Of usssss... Now..."_

"No I'm not." Ta'Gart growled.

 _"Yesss... You are..."_

"I. Am. Not."

 _"Ssssubmit... It is the will... Of the Icon of Sssssin..."_

Something snapped within Ta'Gart's head.

He pounced towards the Imp.

 **"FUCK YOU!"**

Catching the unfortunate demon in a chokehold, Ta'Gart grabbed at its head and shoved it backwards with inhuman force, snapping its neck and killing it. The other two jumped at the former Night Sentinel from behind, but before they could attack, Ta'Gart whipped around with lightning speed and grabbed the creatures in mid-air. Gripping their heads tightly, he smashed them together, causing an eruption of blood, bone and brains that splattered all over his armour.

Time seemed to come to a standstill as the two decapitated corpses fell, limp, into the puddle of flesh that formed on the ground. Ta'Gart's shadow loomed over the fallen; the man took slow breaths as his arms lay limp at his sides. The voices in his head never ceased, and his face still wore an expression of anger.

But his bitter scowl slowly gave way to a maniacal smirk.

"Rip and tear, eh?"

The fact that he could question who he was and had control over his actions (to an extent at least) showed that he still had his consciousness; he had not fallen to the darkness yet.

And while he still had some sense left within him...

There was still hope.

Hope for someone whose soul had gone to the pits of damnation? As absurd as it sounded, it was still true.

Ta'Gart's form started shuddering once again as he gazed down at his blood-soaked hands. Ideas started to form within his mind, which was straining itself trying to ignore the demonic whispers.

A tiny chuckle escaped his throat.

While he still could remember who he was, he knew what he was going to do. Oh, yes. He would hunt down every single demon in existence and turn them into a fleshy red paste. All of Hell will buckle in fear at his very presence; he will turn the Arcane Kingdom itself into dust with his bare hands.

After all, he and his comrades dedicated their entire lives to keeping Argent D'Nur safe from the demons. It was only right that he honored their sacrifices, even in the state he was in.

And once he was done with Hell...

The Incubators were next. The fluffy rat-like bastards who let the demons into his beloved home. He would find their planet and tear up every single one of those creatures. Ta'Gart despised traitors, and the Incubators were traitors of the highest order. Who knows how many more innocent lives they have ruined, or will ruin, by stabbing them in the back? He will give them the rightful punishment a traitor deserves; they will learn right there and then what a Night Sentinel is truly made of.

Ta'Gart got down on one knee and swore a solemn oath. He swore on his life that, to the best of his abilities, he would make good his promises.

For his fallen men.

For his home, Argent D'Nur.

For the Argent people.

And last but not least, for all of the Incubators' victims, past, present and future. No doubt they would continue to prey upon unsuspecting people, but he would make sure that their reign of terror will end one way or another.

Getting up from his crouched position, Ta'Gart picked up the hellish-looking artifact. Upon touching the skull engraving on it out of curiosity, he was amazed when a translucent energy blade, adorned with Argent runes, shot out from one end. He tested the blade within his palm; it felt perfect, even more so than his old sword.

He never felt this pumped up in years. Rage within the vessel of his being gave way to confidence. Just a broken man mere moments ago, he felt whole, and ready to conquer the entire world.

A crazed, cocky grin stretched across his face. Opening his mouth, he issued a challenge from the depths of his tainted heart.

"Hey you demon scum!"

No response. It didn't matter to him; he continued to speak.

"You destroyed my home."

This time, small silhouettes started to form in the distance. Imps, by the look of it, maybe a Pinky or two. He continued his speech.

"You killed my people."

The silhouettes appeared larger. A few Hell Knights and Barons made an appearance as well.

"But you will **NEVER** take my soul! I will crush every single one of you bastards myself, if it's the last thing I do! Both you, and the Incubators! **RIP. AND. TEAR!** "

A cacophony of demonic cries answered his guttural call. Like a tidal wave, the demons started pouring from the horizon. There could be hundreds, thousands, maybe millions of them. Ta'Gart didn't care. He knew he could handle this.

His voice dropped to a whisper.

 _"I'm not a man."_

The demons did not halt their stampede.

 _"I'm not a demon."_

Their deafening roars and the pounding of their feet filled the empty desert.

 _"I..."_

Screeching imps. Growling Hell Knights.

 _"Am..."_

Squealing Pinkies. Howling Arch-Viles.

Ta'Gart grabbed his sword and, with renewed vigor, rushed at the incoming horde headlong to meet them.

 _ **"THE DOOM SLAYER!"**_

* * *

 **A/N**

 **For those of you waiting for Arrogance Of Mann - rest assured, I'll be resuming work on it soon, though updates may still take some time. Thank you for bearing with me all this while.**

 **A friend of mine inspired to make this just yesterday. Based on his prompt, I thought... the Incubators probably worked on other lifeforms and genders before settling on teenage human girls, so... what if they played around with the people of Argent D'Nur, and Doomguy was one of their victims? I finished this story rather quickly - it was originally meant to be quite short, but I got carried away and decided to make it more expansive. And here we go.**

 **Till next time.**

 **\- Beitrik**


End file.
